A number of techniques are available for treating cardiovascular disease such as cardiovascular by-pass surgery, coronary angioplasty, laser angioplasty and atherectomy. These techniques are generally applied to by-pass or open lesions in coronary vessels to restore and increase blood flow to the heart muscle. In some patients, the number of lesions are so great, or the location so remote in the patient vasculature that restoring blood flow to the heart muscle is difficult. Transmyocardial revascularization (TMR) has been developed as an alternative to these techniques which are directed at by-passing or removing lesions. TMR is performed by boring channels directly into the myocardium of the heart.
In one procedure, a laser catheter is advanced into the left ventricle. Laser radiation is then focused on the myocardium to create a channel. It has been found that creating several channels may be helpful. Lasers used to performed TMR can be costly and the depth of the channels can be difficult to control.
TMR has been performed by forming channels with laser energy as described above. TMR has also been performed by cutting a channel with a sharpened probe or blade. The channels cut by laser have a width proportional to the width of the focused laser radiation used to make the channels. When a laser is used, tissue is vaporized to form the channel, when the procedure is performed with a blade, tissue is not removed, but is merely pierced or cut.
Removing, or in the case of TMR laser techniques, vaporization of tissue is believed to enhance of the success of the TMR procedure. Removing tissue, however, by mechanical means has proved difficult.